- the first in counterclockwise order of the bases from home plate.
- the position of the player covering the area of the infield near first base.
- get to first base, Informal.
- to succeed in the initial phase of a plan or undertaking: His suggestions for labor-saving techniques never got to first base.
- to engage in petting that goes no further than kissing.
- the base that a runner must reach safely to score a hit, and the first of the three bases he must reach safely on the way to home plate in order to score a run
- the fielding position nearest this base
- get to first base informal, mainly US and Canadian to accomplish the first step of an undertaking